The problem Innovator is that our idea of a fair wage is different from the rest of the world. How much value a customer puts on a project depends on their reference point. Eugene wants to sell "widgets" at a flea market. If it takes him four hours to make a widget, using your example, he would need to sell his widget for $210. The problem is, the customer has seen similar China-made widgets at Wal-Mart for $19.95. They have a reference point and are not willing to pay what they consider, and rightly so, a ridiculous price.
Craft shows are really tough this year. I would imagine flea markets would be even worse for our products. Normally, customers at flea markets are looking for deals and customers at craft shows are looking for uniqueness and quality (and a funnel cake). From my experience, the only people making money at craft shows this year are the food vendors. You have to have something that is very different than what customers see in the variety stores.
As far as cost Eugene, I am assuming that you are building your projects in your garage. If this is the case, then I wouldn't get too wrapped around overhead and the other stuff at this point. You are already paying for insurance, electricity, water, and all the other costs associated with your home, so other than your electricity cost possibly increasing a little, nothing else changes. Your materials cost is the most important thing you need to know. Figure out the board foot material for each project, and multiply that by your wood cost. Add a small percentage of that cost to cover finish, sandpaper, etc. For example, if your materials cost for a project is $15.00, add 5% (.75), so it now costs $15.75 in materials to produce your "widget". You may need to increase the percentage depending on the amount of finish or sand paper. You also need to add any hardware costs such as hinges, latches, etc. Doing it this way makes it simpler to adjust up or down for material price changes. Labor is easy. Just decide what you want to make per hour and add that in. This number will be your cost to produce the widget.
This is where a lot of people stop figuring and is the reason why you see Wood Whisperer cutting boards being sold on Etsy for $35.00. Labor is not profit. Labor is what you are compensating yourself to build a widget. It takes gas to go pick up lumber. It takes money to rent a booth space at shows, and I am assuming they charge for spaces at flea markets. It also takes money to buy more lumber and hardware. Once you have your cost to produce the widget, you need to add a percentage for profit so you can buy more wood, pay for gas, and pay booth fees. There can be many other costs, but you tend to control them, and I'm trying to keep this example simple. The percentage for profit can be 20%, 30%, 40%, etc. It's up to you to determine what you need to recover to replenish your supplies or buy gas.
Forgetting the profit issue, once you have the widget "cost", look at the number and ask yourself "How can I reduce this cost?". You either find a cheaper source for wood, and/or produce more widgets in a given time to lower the effective labor cost per widget. Doing this will give you more profit or allow you sell at a lower cost and appeal to a wider audience. Either way, you have to stumble around a little initially to get a feel for what makes sense and works for you.